A finished floor typically consists of a sub-floor and a flooring surface, supported by the sub-floor. The nature of a sub-floor will vary depending on the flooring surface it needs to support and the environment in which it must function. For example, for linoleum tile or carpet on a main floor of a house, the sub-floor may simply consist of sheets of plywood. For a ceramic tile floor a cement layer will typically also be required.
Basement flooring presents additional challenges, one of which is the possibility of moisture being present and another which is to insulate the floor from what could be a very cold underlying surface of poured concrete. Fixed sub-floors or “non-floating” sub-floors can be used in basement applications. This type of flooring may have an underlying sheet of semi rigid plastic having depending protrusions over which is placed a series of plywood panels. The panels are securely fixed to the underlying floor using concrete bolts. Fixed sub-floors may be rather labour intensive to install and rely on secure and frequent fastening to prevent movement between adjacent flooring sheets.
U.S. Pat. No. 4,945,697 to Ott et al. which teaches a floor tile and floor for direct installation on a support such as a floor or walkway without a sub-floor. This patent teaches a floor system that uses floor tiles comprised of two layers, an upper layer made of ceramic material and a lower layer made from resilient material with anti-skid characteristics. The two layers are secured together to form a floor tile. The lower layer includes drainage channels on the underside, that allow the passage of water underneath the floor tiles. When used outside, the tiles are spaced apart with gaps between adjacent tiles to allow vertical movement between the tiles. When the floor tiles are used indoors, the gap between adjacent tiles is filled with a flexible material that allows vertical shifting of the tiles. These tiles will not provide a rigid sub-floor layer that would be capable of use in a sub-floor application for supporting a further rigid floor layer on top of the tiles, since any vertical motion between adjacent tiles would cause the further floor layer to crack.
Another example of a non sub-floor application is U.S. Pat. No. 5,950,378 to Council et al. This patent describes a composite modular floor tile for use in athletic playing surfaces such as basketball courts and tennis courts. The floor tile has a top and a bottom member with support nodes extending from the bottom member which provide an air circulation space underneath the floor tiles. The bottom member is made from a resilient impact absorbing material that would not provide a rigid supporting layer and therefore would not be suitable in a sub-floor application.
Accordingly, it is an object of the present invention to provide a sub-floor panel capable of supporting a floor that will allow moisture drainage and air circulation between the tiles and the underlying surface.